The present invention relates to a coin changer utilized in a vending machine which is capable of accepting and storing different coin denominations and in particular to a coin changer having a coin detection device for coin detection and discrimination.
Vending machines typically include coin changer devices for accepting coins of different denominations. These coin changer devices function to authenticate each of the coins inserted into the vending machine and to determine the denomination of each of the coins. Known coin detection devices utilize various coin detection techniques and methods which include optical size detection and metallic content or characteristic detection. Examples of two such coin detection devices are disclosed in U.S Pat. Nos. 4,625,852 and 4,646,904. In operation, a deposited coin is routed along a coin path to pass by either optical sensors or inductive sensors. The optical sensors typically include a phototransistor having a light emitting diode. As the coin rolls by the optical sensor the transmitted light produced by the light emitting diode is blocked from reaching the phototransistor by the coin and a signal representative of this event is sent to the coin changer device. This signal or the duration of this signal may be used to determine the size of the coin. The inductive sensors produce magnetic fields which interact with the coin. The characteristics of the magnetic fields are dependent upon the resistivity and permeability of the coin material as well as the coin size. The signal generated from the interaction of the coin with the magnetic field produced by the inductive sensor can be compared with predetermined unique characteristics for each coin type to be examined by the coin changer device. If the generated signal matches certain characteristics for a particular coin type, then the deposited coin is identified as being that particular coin type.
Although optical sensors and inductive sensors are useful in determining authenticity and denomination of a deposited coin, these sensors typically take up room in the coin changer device in which space is at a premium. Further, it is desirable to utilize small sensing units in vending applications for various reasons. Small sensing units are desirable for coin detection because these units may be positioned close to the coin path for greater magnetic coupling with the coin passing by the inductive sensors. Greater magnetic coupling results in higher magnitude signals being induced in the inductive sensors which results in more accurate coin type identification.
Accordingly, it is desirable and advantageous to provide a coin detection device having small sensing units which are employed to authenticate and accept coins of different denominations. Additionally, it would be advantageous to have a coin detection device which is more accurate in determining coin authenticity and denomination.